This invention relates to apparatus and methods for monitoring the audiences of television programs.
Advertising rates for commercials of television programs are determined by the expected size of the viewer audience. These expectations are usually determined by the estimated audience sizes of the previously broadcast shows. For example, a weekly television series will estimate its audience size for upcoming episodes based on the estimated viewers of previously broadcast shows. Advertising rates may be adjusted based on an "after the fact" estimation of the market share for the televised program. The present systems for estimating market share involve survey evidence such as the Neilson ratings. The Neilson ratings are determined by selected households which record their viewing habits. For example, a selected household might record in a written journal or diary when they turn on and off the television, what channels are selected and the number of viewers in the room. The viewership data may alternately be collected by providing the user with an electronic device which will record the time the television is on and the channel selected. In one implementation, the user is provided with a remote controller, or there is a button on the electronic device, that the user pushes when turning on and off the television. The channel tuner is monitored electronically to determine the channel selected.
Television in the United States is broadcast in a frame format with the odd number lines being scanned during the first field of a frame and the even number lines being scanned during the second field of a frame. Between fields it is necessary for the beam to move or fly back to the upper left corner or upper middle of the screen. During the fly back interval in which the beam returns to the top, the picture on the television is blank. This period of time is called a vertical blanking interval (VBI). The vertical blanking interval can be used to broadcast additional information. For example, close captioning for the deaf is broadcast during a portion of the vertical blanking interval.
The vertical blanking interval can be used to broadcast program information synchronous with the program being transmitted. For example, the title of the program, channel number and time of the broadcast can all be broadcast in the vertical blanking interval. Electronic devices are available for audience monitoring that can decode the vertical blanking interval and read the program information from the vertical blanking interval and store it in a memory. Then on command the memory can be dumped over a telephone line to a central computer for analysis. A shortcoming of this approach is that the program information requires an extensive amount of the vertical blanking interval. It is important to efficiently use the limited vertical blanking interval, because there are increasing demands to include other information in the vertical blanking interval, such as an electronic television guide.
Accordingly, there is a need in the art for an apparatus and method for using compressed codes for audience monitoring, which would consume significantly less of the vertical blanking interval than the combination of a channel number and a time of broadcast for a program. There is also the need in the art for reducing the amount of information which must be stored in an electronic device for audience monitoring and for reducing the amount of information that must be transmitted over telephone lines from the audience monitoring device to a central computer facility.